1. Field of the Invention
This invention relates to dry good material feeding devices which are used for dispensing or conveying powders and bulk dry materials such as chemicals. More particularly, this invention relates to an improved seal for where a drive shaft enters into the hopper of such a device, which provides longer lasting and more effective protection against leakage of the dry material than those seals which were heretofore known.
2. Description of the Prior Art
Dry good material feeders of the type which are manufactured at Tecnetics, Inc. of St. Paul, Minn. which is the assignee of this application, commonly include a hopper having an inclined storage area and a lower cylindrical portion for housing a rotating auger. The rotating auger conveys dry material such as a powdered chemical from the inclined holding area through a cylindrical passage to a space outside of the hopper. In order to provide the mechanical energy which is necessary to turn the auger, most prior art arrangements utilize a drive arrangement which extends from the opposite end of the auger from the direction in which the dry material is conveyed.
To ensure that the dry material does not escape into the drive mechanism for the rotating auger, it is necessary to place some type of a seal between the drive shaft and the housing. However, due to a number of factors, such seals were often susceptible to premature failure. Because the drive shaft seal was at the bottom of the hopper, the dry material which was to be conveyed was often forced up against the seal at a relatively high pressure, which hastened degradation of the seal. In addition, the constant vibration imparted to the seal by the auger via the drive shaft often loosened the seal, which allowed the dry matter to enter into the drive mechanism for the auger. Yet another reason for seal failure was the wear which took place on the seal when the seal needed to be withdrawn from the hopper, such as for maintenance.
It is clear that there has existed a long and unfilled need in the art for an improved sealing arrangement for dry good feeders which provides reduced dry good pressure in the area immediately next to the seal, which provides increased isolation of the seal from shocks which are imparted to the auger during operation, and which can endure more cycles of seal removal.